Electrocatalytic Deuterated Nitric Acid Reduction to Deuterated Ammonia

ABSTRACT Electrocatalytic nitrate (NO 3 − ) deuteration reaction (ENDR) offers a sustainable route for the distributed synthesis of deuterated ammonia (ND 3 ). Present studies focus on alkaline electrolytes, which suffer from excessive cell voltage due to the high D 2 O dissociation energy. The deuterated nitric acid (DNO 3 ) solution can supply an abundant D 3 O + source and be easily formed via NO x direct absorption in pure D 2 O. However, the acidic condition inevitably triggers the competing deuterium evolution reaction (DER) and severe electrocatalyst deactivation. Herein, we design and construct low‐coordinate Rh nanoclusters anchored on mesoporous carbon spheres (Rh NCs/MCS), which exhibits an outstanding long‐term ENDR stability over 200 h with a Faradaic Efficiency exceeding 80% in pure DNO 3 . A series of characterizations reveal that low‐coordinate structure enhances the adsorption of *NO 2 , while the MCS could accumulate nitrite and decrease D 3 O + concentration near Rh active sites. The dual‐positive effects could boost the ND 4 + selectivity and inhibit the competing DER. Furthermore, a high ND 4 + yield (6.15 mmol h −1 ) at industrial current densities (240 mA cm −2 ) is achieved in a scaled‐up electrolytic system. This work establishes a new paradigm for distributed ND 3 synthesis and provides a universal principle for designing robust acidic electrocatalysts.